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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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 Posted: Wed Aug 24, 2016 2:50 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
No problem, I'm leaning what facts are important to bring to the table when solving for CR now.
For instance, I foolishly did not think about measuring the deck height of the pistons when I disassembled my engine... I still have the old heads and P&Cs marked so I could mock up the engine again. I don't have space to do this at home or a friends garage so I am basically paying someone by the hour to work on it myself in their space.
If I can avoid it I rather not mock up these again. I can CC the old heads and I'll put one piston on the block when I get back there, but not all 4.
I thought there would be an easily accessible stock CR number to find but I can't find it anywhere! I can only find the compression in PSI, not the compression ratio... Is there a conversion for this? |
I know ...its odd...I can't seem to find compression ratio numbers for the vanagon anywhere. Ray |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Aug 24, 2016 2:56 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Wed Aug 24, 2016 3:15 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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f*ck me. So I guess I could have left it all as it was and using just a stock AMC head I could have swapped them out without having to flycut the lip off if anything went wrong. But at least now I am getting the correct DH from piston to jug.
Is 7.6-7.7 going to be too high or am I making a sweet little engine? And basically just going to fail emissions for me? Should I be going up to a 0.03" shim so I drop the DH to 0.05" that only brings the compression to 7.5:1
Granted my emissions tech didnt notice that the EGR didnt exist (was rusted to pieces), but I have a replacement for it
edit: I guess the real concern with higher compression is detonation? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Aug 24, 2016 4:24 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
f*ck me. So I guess I could have left it all as it was and using just a stock AMC head I could have swapped them out without having to flycut the lip off if anything went wrong. But at least now I am getting the correct DH from piston to jug.
Is 7.6-7.7 going to be too high or am I making a sweet little engine? And basically just going to fail emissions for me? Should I be going up to a 0.03" shim so I drop the DH to 0.05" that only brings the compression to 7.5:1
Granted my emissions tech didnt notice that the EGR didnt exist (was rusted to pieces), but I have a replacement for it
edit: I guess the real concern with higher compression is detonation? |
No ....detonation is not the issue.
And 7.7:1 should be fine.....it will probably run just a bit better in hydrocarbons and you can drop your ignition timing back about 2 degrees and adjust idle back up and you will be better on NOX. Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Wed Aug 24, 2016 4:28 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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haha so this engines don't get quite hot enough for detonation?
Any idea what is too high of a compression ratio for the stock bottom end? And what issues do you run into when you have too high of a compression ratio? All the issues that come with overheating? So drop/sunken seats mainly? Where do I have to drive more cautiously with a high CR?
Guess I'll have to learn about adjust idle now!  |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26790
Location: Colorado Springs
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| Posted: Wed Aug 24, 2016 6:53 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
| haha so this engines don't get quite hot enough for detonation? |
Sometimes.
| mrcool wrote: |
Any idea what is too high of a compression ratio for the stock bottom end? |
The bottom end could handle 12-1, really has nothing to do with it, it has to do with detonation, (fuel octane VS VE, rpm, temperatures)
| mrcool wrote: |
And what issues do you run into when you have too high of a compression ratio? |
Detonation= let off the gas, retard the timing, try again. Keep an ear on it. If you use the "turn up radio" approach then it will self destruct. Why is it knocking? lets find out. Maybe it's too hot, maybe you have bad gas, maybe the timing is off, maybe it's too lean. If it's TUNED in, you should be able to run 8-1 CR in a near stock engine most all conditions, but there is less margin for error.
A low CR gives you a large margin to keep driving when things are out of whack, but you GIVE UP a lot of power and response, and efficiency. John Connoly quote: "What do you call an engine with zero compression ratio?....
a heater!" Compression is what makes it an engine.... it's important!
I went looking for a graph, but didn't find one, so I made one. Maybe it's worth 500 words. 250?
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jberger
Samba Member
Joined: November 17, 2003
Posts: 2476
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| Posted: Wed Aug 24, 2016 6:59 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| Don't worry about smog.. I have several high-ish compression type IV's in the bay area that pass smog beautifully. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Aug 24, 2016 9:14 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| As Modok noted....its not the mechanicals that you are worried about. There are lots of options open to you. The type 4 is a tough engine. This limiting factor on what you can do is california emissions. Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Wed Aug 24, 2016 9:57 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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Thank you guys for the explanation and reassurance. That diagram was very helpful Modok! At least I am aware that I will have a higher than stock CR. I just now need to seriously learn how to tune it. Luckily I don't have a radio in my van so I should be able to hear it
I have TDC marked down and the distributor is in the correct position so that the 1 notch is right on TDC. I guess one of the first things I need to do is a compression test but those numbers are going to be funky until the rings break in.
Do you guys install CHT gauges? I am toying with the best way to install one on mine. The head is out but the machine shop doesn't want to counter bore a hole in the spark plug socket for it... I think because they haven't done so before.
I just cleaned the pistons tonight. dang aviation sealant is really nice to take off with isopropyl alcohol. But I will be using ultra-grey sealant this time around.
Anyone vote for going with a deck height higher than 0.04" to reduce the CR? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Aug 25, 2016 7:03 am Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
Thank you guys for the explanation and reassurance. That diagram was very helpful Modok! At least I am aware that I will have a higher than stock CR. I just now need to seriously learn how to tune it. Luckily I don't have a radio in my van so I should be able to hear it
I have TDC marked down and the distributor is in the correct position so that the 1 notch is right on TDC. I guess one of the first things I need to do is a compression test but those numbers are going to be funky until the rings break in.
Do you guys install CHT gauges? I am toying with the best way to install one on mine. The head is out but the machine shop doesn't want to counter bore a hole in the spark plug socket for it... I think because they haven't done so before.
I just cleaned the pistons tonight. dang aviation sealant is really nice to take off with isopropyl alcohol. But I will be using ultra-grey sealant this time around.
Anyone vote for going with a deck height higher than 0.04" to reduce the CR? |
No.....increasing the deck increases hot running ....mostly piston head temp at higher rpms.
LEAVE THE DECK ALONE......the compression is much easier to control with shims.
Undersand.....its not just compression the deck height affects.
1. It affects compression ratio
2. If its to small it can affect pjston to bead clearance which = bent valves
3. If the deck is too large it puts the frame front farther out of the conbustion chamber and deeper into the cylinder......this bearkng in mind that with ignition advance. .....you are already starting the flame when the piston is some distance down the cylinder on its way up.
There are a few ways for CHT. The most common method requires no machine work...only a little work with a die grinder to make a notch in the side of the counterbore for the crimp and the wire. Put the ring terminal under the spark plug. Its the most accurate.
I have another way of installing a ring terminal I am working on......but I have not finished it yet and it has some risks so I will not outline it publicly until I have tested it.
What is it you are asking your machine shop to counterbore? Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Thu Aug 25, 2016 9:02 am Post subject: Re: Type 4 - Compression Ratio Numbers |
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| raygreenwood wrote: |
| mrcool wrote: |
Thank you guys for the explanation and reassurance. That diagram was very helpful Modok! At least I am aware that I will have a higher than stock CR. I just now need to seriously learn how to tune it. Luckily I don't have a radio in my van so I should be able to hear it
I have TDC marked down and the distributor is in the correct position so that the 1 notch is right on TDC. I guess one of the first things I need to do is a compression test but those numbers are going to be funky until the rings break in.
Do you guys install CHT gauges? I am toying with the best way to install one on mine. The head is out but the machine shop doesn't want to counter bore a hole in the spark plug socket for it... I think because they haven't done so before.
I just cleaned the pistons tonight. dang aviation sealant is really nice to take off with isopropyl alcohol. But I will be using ultra-grey sealant this time around.
Anyone vote for going with a deck height higher than 0.04" to reduce the CR? |
No.....increasing the deck increases hot running ....mostly piston head temp at higher rpms.
LEAVE THE DECK ALONE......the compression is much easier to control with shims.
Undersand.....its not just compression the deck height affects.
1. It affects compression ratio
2. If its to small it can affect pjston to bead clearance which = bent valves
3. If the deck is too large it puts the frame front farther out of the conbustion chamber and deeper into the cylinder......this bearkng in mind that with ignition advance. .....you are already starting the flame when the piston is some distance down the cylinder on its way up.
There are a few ways for CHT. The most common method requires no machine work...only a little work with a die grinder to make a notch in the side of the counterbore for the crimp and the wire. Put the ring terminal under the spark plug. Its the most accurate.
I have another way of installing a ring terminal I am working on......but I have not finished it yet and it has some risks so I will not outline it publicly until I have tested it.
What is it you are asking your machine shop to counterbore? Ray |
Maybe I misspoke. I am not sure exactly what leaving the deck alone is. But the deck height changes when I use different shims.
Right now the 0.030" lip is being removed. That means my deck height from piston to jug is 0.029" with a 0.009" shim included in that measurement. Without the shim we are at 0.020" so I want to put a 0.020" shim for a total height of 0.040" which is the bottom of the spec and gets me a CR of 7.7:1. I was asking if I should go to a 0.030" or 0.040" shim so I get a DH of 0.050" or 0.060" and lower the compression ratio.
But it sounds like I am fine with a 7.7CR and just have to learn how to properly tune my van.
I wanted the machine shop to counter bore the width of the CHT thermocouple so I wouldn't have to cut off the spark plug washer to achieve the correct height. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Aug 25, 2016 9:41 am Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
| raygreenwood wrote: |
| mrcool wrote: |
Thank you guys for the explanation and reassurance. That diagram was very helpful Modok! At least I am aware that I will have a higher than stock CR. I just now need to seriously learn how to tune it. Luckily I don't have a radio in my van so I should be able to hear it
I have TDC marked down and the distributor is in the correct position so that the 1 notch is right on TDC. I guess one of the first things I need to do is a compression test but those numbers are going to be funky until the rings break in.
Do you guys install CHT gauges? I am toying with the best way to install one on mine. The head is out but the machine shop doesn't want to counter bore a hole in the spark plug socket for it... I think because they haven't done so before.
I just cleaned the pistons tonight. dang aviation sealant is really nice to take off with isopropyl alcohol. But I will be using ultra-grey sealant this time around.
Anyone vote for going with a deck height higher than 0.04" to reduce the CR? |
No.....increasing the deck increases hot running ....mostly piston head temp at higher rpms.
LEAVE THE DECK ALONE......the compression is much easier to control with shims.
Undersand.....its not just compression the deck height affects.
1. It affects compression ratio
2. If its to small it can affect pjston to bead clearance which = bent valves
3. If the deck is too large it puts the frame front farther out of the conbustion chamber and deeper into the cylinder......this bearkng in mind that with ignition advance. .....you are already starting the flame when the piston is some distance down the cylinder on its way up.
There are a few ways for CHT. The most common method requires no machine work...only a little work with a die grinder to make a notch in the side of the counterbore for the crimp and the wire. Put the ring terminal under the spark plug. Its the most accurate.
I have another way of installing a ring terminal I am working on......but I have not finished it yet and it has some risks so I will not outline it publicly until I have tested it.
What is it you are asking your machine shop to counterbore? Ray |
Maybe I misspoke. I am not sure exactly what leaving the deck alone is. But the deck height changes when I use different shims.
Right now the 0.030" lip is being removed. That means my deck height from piston to jug is 0.029" with a 0.009" shim included in that measurement. Without the shim we are at 0.020" so I want to put a 0.020" shim for a total height of 0.040" which is the bottom of the spec and gets me a CR of 7.7:1. I was asking if I should go to a 0.030" or 0.040" shim so I get a DH of 0.050" or 0.060" and lower the compression ratio.
But it sounds like I am fine with a 7.7CR and just have to learn how to properly tune my van.
I wanted the machine shop to counter bore the width of the CHT thermocouple so I wouldn't have to cut off the spark plug washer to achieve the correct height. |
I have a possible solution for your thermocouple issue.....but its not really for the machine shop.....and you will have to make a new larger crimp on ring for your thermocouple.
So....find a thicker shim....they are available....or simply use two .009" shims. Then your deck is set.
This is why people get confused. They keep mixing terminology. ..as and all these different calculator sites are the worst.
Your deck is your deck. Thats between top of piston....and the top of the jug....ONLY.
That 0.30" ring....is attached to the combustion chamber. Its an extension of the combustion chamber....it gets cc'd with the combustion chamber.
In your last post you noted....."anyone vote for going with a deck height heigher than .040" to reduce compression ratio"?
Set your deck ....the real deck....the only,deck.....at .040"....with either one shim or a pair of .009" shims......and leave it .....for now.
When you get your heads back.....cc the chambers and recalculate your compression ratio.
If it needs to be increased.....just a small amount....you can reduce the shim thickness and go to an absolute minimum of .035" deck. If it needs just a little less....you can re-mix the shim pack and go to .045 absolute maximum.
Any other changes require going back to the machine shop for a skim.
Bear in mind.....you have to take the jugs off again anyway to lap them into the heads.
Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Thu Aug 25, 2016 12:48 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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Ok great! Don't use the deck height to set the CR other than between 0.035" and 0.045". Use the combustion chamber for the CR changes.
The two things I now have to figure out is
1) is there a better way to set the piston rings w/ higher CR?
I have bottom most ring at 1 oclock, then the next ring is about 5, then the top most ring is back between 1 and 2.
2) Tuning. Are there any good sources on this? Just read and re-read the L-jet manual? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Aug 25, 2016 1:11 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
Ok great! Don't use the deck height to set the CR other than between 0.035" and 0.045". Use the combustion chamber for the CR changes.
The two things I now have to figure out is
1) is there a better way to set the piston rings w/ higher CR?
I have bottom most ring at 1 oclock, then the next ring is about 5, then the top most ring is back between 1 and 2.
2) Tuning. Are there any good sources on this? Just read and re-read the L-jet manual? |
There are not going to be any useful manuals for tuning D-jet or L-jet. There are some very good manuals out there...most notably the Probst fuel injection manual...but those tell you how the systems work...and how to keep them running as the factory intended them to be....but nothing about how to get those same parts to work when you have changed the engine parameters.
Bear in mind you have a system from a 2.0...right?....and you are not far off of that. You may have very little tuning to do.
We can get into that when you have a running engine.
I don't know where you found ring spacing instructions...  but that sounds kind of odd. The object is to space them as far apart from each other as possible to keep the gaps from lining up and causing a direct path for gasses. Space them at 120* apart.
The oil rails or upper and lower rings that make up aa three piece oil ring ...just space between the other gaps. Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Thu Aug 25, 2016 1:56 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| raygreenwood wrote: |
| mrcool wrote: |
Ok great! Don't use the deck height to set the CR other than between 0.035" and 0.045". Use the combustion chamber for the CR changes.
The two things I now have to figure out is
1) is there a better way to set the piston rings w/ higher CR?
I have bottom most ring at 1 oclock, then the next ring is about 5, then the top most ring is back between 1 and 2.
2) Tuning. Are there any good sources on this? Just read and re-read the L-jet manual? |
There are not going to be any useful manuals for tuning D-jet or L-jet. There are some very good manuals out there...most notably the Probst fuel injection manual...but those tell you how the systems work...and how to keep them running as the factory intended them to be....but nothing about how to get those same parts to work when you have changed the engine parameters.
Bear in mind you have a system from a 2.0...right?....and you are not far off of that. You may have very little tuning to do.
We can get into that when you have a running engine.
I don't know where you found ring spacing instructions... but that sounds kind of odd. The object is to space them as far apart from each other as possible to keep the gaps from lining up and causing a direct path for gasses. Space them at 120* apart.
The oil rails or upper and lower rings that make up aa three piece oil ring ...just space between the other gaps. Ray |
I got those from Jake Raby on his Type 4 rebuild video... haha. Dang... So doing 120 degrees for each would put oil ring gap at top, then the wiper ring towards bottom right then compression ring gap between 10-11. I just want them 120 apart and not in line with the wrist pins. Also try to off set it so the gap isnt at the very bottom of the piston?
edit: correct, I have a 2.0 FI |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Aug 25, 2016 3:24 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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Jake knows more than I do by by far....by far.
However....make sure that his combo is the same as yours. Most diagrams you find on line ....and the way I was taught and have never had issues.....is one ring at 12.....one at about 4 or 4.5....120° from 12 oclock.....another at around 7 or 7.5.....again 120° from 12 oclock. ...and the oil rail gaps.....midway between 12 oclock and and 7.5 and 12 oclock and 4.5......if that lines them up with wrist pins.....close enough. I have a diagram from somewhere that I will post in the am. Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Sun Aug 28, 2016 5:08 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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Ok so the heads are back and looking nice and shiny. I lapped the cylinders to the heads and then CC'ed them again.
I was measuring 52ml across the board.
That puts my numbers at
Bore - 94mm
Stroke - 71
DH - 0.038 to 0.04 (waiting on 0.02" shims for this)
CC - 52ml (head) + 15ml (piston) = 67
CR = 7.6-7.7
0.009" std shims seem to be more accessible but I rather not stack two of them.
If you guys have any tips on using Ultra-Grey silicon to seal the cylinders/gaskets to the case that would be great. I'm trying to get this one perfect the first time
I found this on the permatex information so that helps
| Quote: |
Assemble parts immediately while silicone is still wet.
Secure or tighten to recommended torque specs.
Re-torque will not be necessary after the product has
cured. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Sun Aug 28, 2016 7:42 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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| mrcool wrote: |
Ok so the heads are back and looking nice and shiny. I lapped the cylinders to the heads and then CC'ed them again.
I was measuring 52ml across the board.
That puts my numbers at
Bore - 94mm
Stroke - 71
DH - 0.038 to 0.04 (waiting on 0.02" shims for this)
CC - 52ml (head) + 15ml (piston) = 67
CR = 7.6-7.7
0.009" std shims seem to be more accessible but I rather not stack two of them.
If you guys have any tips on using Ultra-Grey silicon to seal the cylinders/gaskets to the case that would be great. I'm trying to get this one perfect the first time
I found this on the permatex information so that helps
| Quote: |
Assemble parts immediately while silicone is still wet.
Secure or tighten to recommended torque specs.
Re-torque will not be necessary after the product has
cured. |
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I will write you up a method I have written a lot about...in the am. If you apply the ultra gray to each side of the shim with a rubber roller....it makes a perfectly textured, perfectly even layer....about .0001" thick. Let it dry.....do the other side....let it dry. Give it one more fast roll wet on dry both sides before installing.
It creates an actual precision gasket that does not squeeze out. This is actually how certain types of thin precison gaskets are made. Ray |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Tue Aug 30, 2016 8:10 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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Hope you see this raygreenwood.
I wasn't able to bring up that method in any of the searches. Was there anything more complex to it than you described? I'm ready for the install tomorrow! Thanks!
edit: I found this thread by searching rubber roller haha.
http://www.thesamba.com/vw/forum/viewtopic.php?t=6...p;start=20
The second page has some awesome explanations! Is Ultra-Grey going to work well with this method? I plan on using it for the oil pump and cylinder to case. |
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mrcool
Samba Member
Joined: April 01, 2015
Posts: 358
Location: Bozeman, MT
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| Posted: Sat Oct 01, 2016 8:35 pm Post subject: Re: Type 4 - Compression Ratio Numbers |
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I don't think there are any loose ends I didn't write up about but I just wanted to thank everyone in this thread for all their help. The van is running a million times better than before I rebuilt it. I also replaced the clutch, and dang it feels great to drive. I only went as far as replacing the rod bearings, so just a top end rebuild. Now I just need to tune the engine and set a valve cover so the gasket stops leaking!
I have hydraulic lifters so no adjustments should be necessary but I still want to check them after 100 miles or so. Just to make sure they arent out of wack.
Thanks again!!!! |
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